Targeting anabolic drugs for accelerated fracture repair

ABSTRACT

Aspects of the disclosure include materials and methods for the targeted delivery of growth factors, and other compounds that stimulate bone growth and in some aspect bone healing. Some aspects of the disclosure include methods for synthesizing and testing these compounds. Some aspects of the invention include methods of using the compounds disclosed herein to treat bone fractures and bone defects.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/678,016, filed on May 30, 2018. This application is incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

Aspects of the present disclosure relate to the materials and methods for treating bone fractures and bone defects.

BACKGROUND

Src tyrosine kinase plays a crucial role in bone metabolism: despite its ubiquitous expression profile, the only apparent phenotypical abnormality in a sarcoma-knockout (Src-KO) mouse strain was osteopetrosis. Although Src inhibitors inhibit both the formation and activity of osteoblasts (OBs) in vitro, the number of osteoclasts (OCs) derived from Src-KO mice were actually elevated in Src-KO mice, measuring more than twice that in wild-type (WT) mice. Also, a marked increase in both osteoblast number and activity was observed in vivo in Src-KO mice. These results confirm that the osteopetrosis phenotype of Src-KO mice was not a result of reduced osteoclast formation, but rather of boosted osteoblast activity as well as reduced osteoclast function. Moreover, osteoblasts derived from Src-KO mice demonstrated unremarkable morphological features compared to those harvested from WT mice, and were able to fully regulate normal osteoclast differentiation via the receptor activator of nuclear factor kappa-B ligand/receptor activator of nuclear factor kappa-B/osteoprotegerin (RANKL/RANK/OPG) pathway. Thus, this bone-resorption defect should be easily alleviated by restoring normal Src functionality in osteoclasts, reducing potential risks on the musculoskeletal system involved in long-term use of Src inhibitors for fracture healing.

Broadly, peptide anabolic drugs include different categories of protein or the fragments thereof. They are represented by bone morphogenetic protein pathway signaling peptides including P4, bone forming peptide (BFP) and peptide from Bone morphogenetic protein 9 (pBMP9); insulin-like growth factor (IGF) derived peptides including mechano-growth factor (MGF) and Preptin; bone stimulatory neuropeptides including Substance P and vasoactive intestinal peptide (VIP); and peptides enhancing vascular functions, including C-type Natriuretic peptide (CNP), thrombin fragment or targeted prothrombin peptide (TP508) and VIP. Each of these peptides may have its own unique mechanism working to regulate bone growth, as will be outlined in the detailed description.

Current clinical treatment of fractures generally does not include the use of site-specific anabolic drugs. In fact, the only drugs approved for clinical use on such fractures are bone morphogenic protein (BMP)-2 (approved for use only in tibial trauma) and BMP-7 (discontinued), which are applied locally and generally used in the treatment of open long bone fractures and spinal fusions. The need for broader application of anabolic drugs to treat bone maladies such as osteoporotic fractures with efficacy is evident.

Therefore, it is desirable to have a fracture treatment drug that is administered systemically yet targets the fracture site with evident efficacy.

SUMMARY

A first aspect of the present disclosure includes at least one compound of the formula X-Y-Z, or a pharmaceutically acceptable salt thereof, or a metabolite thereof, wherein X is at least one agent that improves bone density, mechanical strength, bone deposition, or quality; Z is at least one bone-targeting molecule; and Y is a linker that joins and/or links X and Z. In some aspects, X is at least one agent that enhances the activity or one agent that improves bone density, mechanical strength, bone deposition or otherwise promotes bone healing and/or growth. Consistent with some of these aspects, Z is at least one negatively charged oligopeptide or an equivalent thereof that binds to hydroxyapatite and/or raw bone.

The second aspect includes the compound according to the first aspect, wherein when X is a polypeptide, any polypeptide having at least about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and/or 100% identity to X can be used to practice the invention.

In some aspects, Y is at least one polypeptide comprising at least about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and/or 100% sequence identity to amino acid residues 35-40, 35-41, 35-42, 35-43, 35-44, 35-45, 35-46, 35-47, 35-48, 35-49, 35-50, 35-51, 35-52, 35-55, 35-84, 41-44, 41-45, 41-46, 41-47, 41-48, 41-49, 41-50, and/or 41-84 of a full length parathyroid hormone related peptide or parathyroid hormone, and/or at least one Cathepsin K sensitive polypeptide.

In some aspects, Z is at least one polypeptide comprising about 4 or more, from about 4 to about 100, from about 4 to about 50, from 4 to about 20, from about 4 to about 15, from about 4 to about 10 acidic amino acid residues, polyphosphate, 2-aminohexanedioic (aminoadipic) acid or derivatives thereof, and/or alendronate or derivatives thereof. In some aspects, Z is at least one polypeptide comprising about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and/or 30 acidic amino acid residues, polyphosphate, 2-aminohexanedioic acid or derivatives thereof, and/or alendronate or derivatives thereof. In some aspects, Z is at least one negatively charged oligopeptide or an equivalent thereof that binds to hydroxyapatite and/or raw bone.

The targeted delivery strategy recited in some aspects of the invention enable the delivery of Src inhibitors specifically to bone fracture surfaces thereby facilitating fracture healing. This in vivo efficacy is shown by the acceleration of fracture healing observed using the Src inhibitors Dasatinib and E738.

In addition to Src inhibitors, a group of peptides targeted specifically to the fracture surfaces also demonstrates an enhanced ability to facilitate fracture healing. These peptides include osteopontin derived fragments such as osteopontin-derived peptide (ODP), collagen binding motif (CBM); BMP fragments such as P4, BFP, pBMP7; IGF fragments such as MGF and Preptin; neuropeptides such as Substance P and VIP; Vasoconstrictive fragments such as CNP, TP508 and VIP; and other anabolic drugs such as osteogenic growth peptide (OGP).

The in vivo efficacy of these peptides for accelerated fracture healing are demonstrated herein. All peptide conjugates are produced by solid phase synthesis.

Some aspects of this disclosure include compounds comprising: a compound of the formula X-Y-Z, wherein X is at least one agent that modulates bone growth, such as activity of Src tyrosine kinase; Z is at least one bone-targeting molecule; and Y is a linker that joins and/or links X and Z; or a pharmaceutically acceptable salt thereof, or a metabolite thereof. In some aspects, Z is at least one polypeptide comprising 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and/or 20 acidic amino acid residues. In some aspects, X is selected from the group consisting of Dasatinib and E738. In some aspects, Y is a releasable linker selected from disulfide; ester; or protease specific amide bond. In some aspects, Y is a nonreleasable bond selected from carbon-carbon bond; or amide bond.

In some aspects, this disclosure includes a compound of the formula X-Y-Z, wherein X is at least one peptide or a fragment thereof that modulates activity of bone and cartilage formation; Z is at least one bone-targeting molecule; and Y is a linker that joins and/or links X and Z; or a pharmaceutically acceptable salt thereof, or a metabolite thereof. In some aspects, Y is a releasable linker selected from disulfide; ester; or protease specific amide bond. In some aspects, Y is a nonreleasable bond selected from carbon-carbon bond; or amide bond. In some aspects, Y is a peptide belonging to the natural sequence of Z. In some aspects, Y is a polyethylene glycol (PEG) linker. In some aspects Y is a PEG linker comprised of 2-8 oxyethylene units. In some aspects, Z comprises at least 10 aspartic or glutamic acids conjugated to X. In some aspects, Z comprises at least 20 aspartic or glutamic acids conjugated to X. In some aspects, the compound may be produced by solid phase synthesis.

In some aspects, X is a bone anabolic peptide derived from BMP. In some aspects, X is a bone anabolic peptide derived from IGF. In some aspects, X is a bone anabolic peptide derived from a neuropeptide. In some aspects, X is a bone anabolic peptide that improves vascular function and/or vascularization. In some aspects, X is osteogenic growth peptide (OGP). In some aspects, the peptide is BFP, P4, or pBMP9. In some aspects, the peptide is MGF or Preptin. In some aspects, the peptide is Substance P or VIP. In some aspects, the peptide is TP508, VIP, or CNP. Unless indicated otherwise, the invention may be practiced by combining any X with any Z and optionally any suitable linking group Y.

-   -   1. A compound comprising:         -   a compound of the formula X-Y-Z, wherein         -   X is at least one agent that modulates activity selected             from the group consisting of: Components of the             Extracellular Matrix, Integrin alpha 5 ligands, Laminins,             fibronectins, P3, and fragments of Osteopotin:         -   Z is at least one bone-targeting molecule; and         -   Y is an optional linker that joins and/or links X and Z;             -   or a pharmaceutically acceptable salt thereof, or a                 metabolite thereof.     -   2. The compound according to claim 1, wherein         -   Z is at least one polypeptide comprising 6, 7, 8, 9, 10, 11,             12, 13, 14, 15, 16, 17, 18, 19 and/or 20 acidic amino acid             residues.     -   3. The compound according to claims, 1-2 wherein Z includes         multiple aspartates and/or multiple glutamates.     -   4. The compound according to claim 3, wherein Z is comprised of         at least one polypeptide selected from the group consisting of:         at least 5 aspartic acids, at least 5 glutamic acids, at least         10 aspartic acids, at least 10 glutamic acids, at least 20         aspartic acids, at least 20 glutamic acids.     -   5. The compounds according to claims 1-4, wherein Z is selected         from the group consisting of: a polypeptide comprising 10         aspartic acid residues (SEQ ID NO. 33) and a polypeptide         comprising 10 glutamic acid residues (SEQ ID NO. 34).     -   6. The compound according to claims 1-4, wherein Z is at least         one polypeptide comprising 4 or more acidic amino acid residues,         polyphosphate, aminohexanedioic acid or derivatives thereof,         and/or alendronate or derivatives thereof.     -   7. The compound according to claims 1-6, wherein Y is selected         from the group consisting of: releasable linkers and         non-releasable linkers.     -   8. The compound according to claim 7, wherein the releasable         linker includes at least of the following groups: a disulphide,         an ester, or a Protease specific amide bond.     -   9. The compound according to claim 7, the non-releasable linker         includes at least one of the following groups; a carbon-carbon         bond, or an amide.     -   10. The compound according to claims 1-6, wherein Y is         polyethylene glycol (PEG).     -   11. The compound according to claim 10, wherein the PEG linker         is comprised of 2-8 oxyethylene units.     -   12. The compound according to claims 1-6, wherein Y is a peptide         belonging to the natural sequence of Z.     -   13. The compound according to claims, 1-9, wherein the         Components of the Extracellular Matrix are selected from the         group consisting of: Chemotatic Collagen (CTC), P15, and DGEA.     -   14. The compound according to claims, 1-9, wherein the Integrin         alpha 5 ligands are selected from the group consisting of:         ITGaS_cys, ITGA_stb-KD, ITGA_stb-KE, ITGA_stb-DAPE, and         ITGA_stb-DAPD.     -   15. The compound according to claims, 1-9, wherein the Laminins,         are selected from the group consisting of: Laminin Fragment         (IKVAV) and Ln2-P3.     -   16. The compound according to claims, 1-9, wherein the         fibronectin is the cell binding peptide PHSRN.     -   17. The compound according to claims, 1-9, wherein the         Osteopontin fragments are selected from the group consisting of:         Collagen Binding Motif (1-28), Collagen Binding Motif (1-19),         Osteopontin Derived Peptide, and Collagen Binding Domain.     -   18. Use of a compound according to any of claims 1-17, for the         manufacture of a medicament for therapeutic application.     -   19. A method of treating a patient, comprising the step of         administering at least one dose of a compound according to         claims 1-17.

These and other features, aspects and advantages of the present disclosure will become better understood with reference to the following figures, associated descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the bone volume divided by total volume of the 100 thickest micro computed tomography (CT) slices of the fracture callus bone density (“BV/TV”) using a Dasatinib and targeted Dasatinib conjugate (both 10 mol/kg). Both were subcutaneously dosed daily to fracture-bearing Notre Dame breed (ND4) of Swiss Webster mice. Bone density of the fracture callus from the targeted Dasatinib group is twice as dense as the saline group, and 50% denser than the free Dasatinib group.

FIG. 2 depicts BV/TV and Trabecular Thickness using targeted E738 conjugate (1 μmol/kg), subcutaneously dosed every-other-day to fracture-bearing Charles River's breed (CFW) of Swiss Webster mice. Targeted E738 conjugate significantly improved the bone density and trabecular thickness at the fracture callus.

FIG. 3 depicts structures for Dasatinib and E738.

FIG. 4 depicts structures for targeted conjugates of Dasatinib and E738.

FIG. 5 depicts peak load of Fractured Femurs after 2 weeks.

FIG. 6 depicts BV/TV two weeks after fractured femur received various concentration of Preptin D10 treatment.

FIG. 7 depicts TbTh (the trabecular thickness of the 100 thickest micro computed tomography (CT) slices of the fracture callus) two weeks after fractured femur received various concentration of Preptin D10 treatment.

FIG. 8 depicts BV (the overall bone volume of the 100 thickest micro CT slices of the fracture callus) two weeks after fractured femur received various concentration of Preptin D10 treatment.

FIG. 9 depicts BV/TV two weeks after fractured femur received various concentration of OGPD10.

FIG. 10 depicts TbTh two weeks after fractured femur received various concentration of OGP D10.

FIG. 11 depicts TbSp (the spacing between the trabecula in the 100 thickest micro CT slices of the fracture callus) two weeks after fractured femur received various concentration of OGP D10.

FIG. 12 depicts BV/TV two weeks after fractured femur received various concentration of BFPD10.

FIG. 13 depicts TbSp two weeks after fractured femur received various concentration of BFPD10.

FIG. 14A depicts BV/TV four weeks after a fractured femur received various concentration of substance P4 mini peg D10 (P4 D10); FIG. 14B depicts the max load of substance P4 D10 four weeks after a fractured femur received the max load of substance P4 D10.

FIG. 15 depicts BV/TV four weeks after fractured femur received various concentration of Ghrelin D10.

FIG. 16 depicts BV four weeks after fractured femur received various concentration of pBMP9 D10.

FIG. 17 depicts BV/TV four weeks after fractured femur received various concentration of pBMP9 D10.

FIG. 18 depicts BV/TV four weeks after fractured femur received various concentration of CNP D10.

FIG. 19 depicts BV/TV four weeks after fractured femur received 1 nmol/day of ODP D10.

FIG. 20 depicts BV/TV three weeks after fractured femur received various concentrations of CBM D10 as compared to a fractured femur that received parathyroid hormone 1-34 (PTH).

FIG. 21 depicts BV/TV four weeks after fractured femur received various concentrations of P4 D10.

FIG. 22 depicts BV four weeks after fractured femur received 1 nmol/day of P4 D10.

FIG. 23 depicts BV/TV four weeks after fractured femur received various concentrations of MGF D10.

FIG. 24 depicts BV/TV four weeks after fractured femur received various concentrations of TP 508_D10.

FIG. 25 depicts BV/TV four weeks after fractured femur received 1 nmol/day of VIP_D10.

FIG. 26 depicts TbTh four weeks after fractured femur received 1 nmol/day of VIP_D10.

FIG. 27 depicts the structure for BMP9.

FIG. 28 depicts the structure for Ghrelin D10.

FIG. 29 depicts the structure for Preptin D10.

FIG. 30 depicts the structure for CNP-D10.

FIG. 31 depicts the structure for VIP D10.

FIG. 32 depicts the structure for Substance P with 4 mini PEG conjugated to D10.

FIG. 33 depicts the structure for CBM D10.

FIG. 34 depicts the structure for ODP D10.

FIG. 35 depicts the structure of CTC_peg 10_e10 (SEQ ID NO: 20).

FIGS. 36-37 depict in vivo fracture healing efficacy of CTC_peg10_(D)E₁₀ conjugate.

FIG. 38 depicts the structure of CTC_MP4_e10 (SEQ ID NO: 21).

FIGS. 39-41 depict in vivo fracture healing efficacy of CTC_mp4_(D)E₁₀ conjugate.

FIG. 42 depicts the structure of P15 (SEQ ID NO: 22).

FIGS. 43-44 depict In vivo fracture healing efficacy of P15_(D)E₁₀ conjugate.

FIG. 45 depicts the structure of P15_mp4_e10 (SEQ ID NO: 23).

FIGS. 46-49 depict In vivo fracture healing efficacy of P15_mp4_(D)E₁₀ conjugate.

FIG. 50 depicts the structure of DGEA_mp4_e10 (SEQ ID NO: 24).

FIGS. 51-54 depict In vivo fracture healing efficacy of DGEA_mp4_(D)E₁₀ conjugate.

FIG. 55 depicts the structure of ITGA5 (SEQ ID NO: 25).

FIGS. 56-64 depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate.

FIG. 65 depicts a structure with a stabilized ring of ITGA (SEQ ID NO: 25).

FIGS. 66a and 66b depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Stb(stable) conjugate.

FIG. 67 depicts the structure of ITGA_mp4_e10_DAPE (SEQ ID NO: 25).

FIGS. 68-71 depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate.

FIG. 72 depicts the structure of ITGA_mp4_e10_DAPD (SEQ ID NO: 25).

FIGS. 73-76 depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPD conjugate.

FIG. 77 depicts the structure of ITGA_mp4_e10_KD (SEQ ID NO: 25).

FIGS. 78-81 depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KD conjugate.

FIG. 82 depicts the structure of ITGA_mp4_e10_KE (SEQ ID NO: 25).

FIGS. 83-86 depict In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KE conjugate.

FIG. 87 depicts the structure of IKVAV_mp4_e10 (SEQ ID NO: 26).

FIGS. 88-91 depict In vivo fracture healing efficacy of IKVAV_mp4_(D)E₁₀ conjugate.

FIG. 92 depicts the structure of LN2_P3_mp4_e10 (SEQ ID NO: 27).

FIGS. 93-96 depict In vivo fracture healing efficacy of LN2_P3_mp4_(D)E₁₀ conjugate.

FIG. 97 depicts the structure of PHSRN_mp4_e10 (SEQ ID NO: 28).

FIGS. 98-101 depict In vivo fracture healing efficacy of PHSRN_mp4_(D)E₁₀ conjugate.

FIG. 102 depicts the structure of P3_mp4_e10 (SEQ ID NO: 29).

FIGS. 103-106 depict In vivo fracture healing efficacy of P3_mp4_(D)E₁₀ conjugate.

FIG. 107 depicts the structure of SPARC 113_mp4_e10 (SEQ ID NO: 30).

FIGS. 108-111 depict In vivo fracture healing efficacy of SPARC113_mp4_(D)E₁₀ conjugate.

FIG. 112 depicts the structure of CBM(1-19)-D10 collagen binding motif (SEQ ID NO: 31).

FIGS. 113-115 depict In vivo fracture healing efficacy of CBM(1-19)_D₁₀ conjugate.

FIG. 116 depicts the structure of CBD_MP4_e10 (SEQ ID NO: 32).

FIGS. 117-119 depict In vivo fracture healing efficacy of CBD_MP4_(D)E₁₀ conjugate.

BRIEF DESCRIPTION OF THE SEQUENCES

SEQ ID NO: 1: bone forming peptide conjugated with 10 aspartate acids (BFP D10).

SEQ ID NO: 2: osteogenic growth peptide conjugated with 10 aspartate acids (OGP D10).

SEQ ID NO: 3: Preptin conjugated with 10 aspartate acids (Preptin D10).

SEQ ID NO: 4: substance P with 4 mini PEG linker and conjugated with 10 aspartate acids (substance P 4 mini PEG D10).

SEQ ID NO: 5: Ghrelin D10 with Ser-3 replaced with diaminopropinoic acid.

SEQ ID NO: 6: BMP9 D10.

SEQ ID NO: 7: C-type Natriuretic peptide (CNP) conjugated with 10 aspartate acids (CNP 10).

SEQ ID NO: 8: Vasoactive intestinal peptide conjugated with D10.

SEQ ID NO: 9: collagen binding motif conjugated with 10 aspartate acids (CBM D10).

SEQ ID NO: 10: P4 conjugated with 10 aspartate acids (P4 D10).

SEQ ID NO: 11: Mechano-growth factor conjugated with 10 aspartate acids (MGF D10).

SEQ ID NO: 12: Thrombin fragment TP508 conjugated with 10 aspartate acids (TP 508 D10).

SEQ ID NO: 13: Osteopontin-derived peptide conjugated with 10 aspartate acids (ODP D10).

SEQ ID NO: 14: BMP9 (BMP9).

SEQ ID NO: 15: Ghrelin D10 (Ghrelin D10).

SEQ ID NO: 16: CNP-D10.

SEQ ID NO: 17: VIP D10.

SEQ ID NO: 18: 4 mini PEG D10.

SEQ ID NO: 19: ODP D10.

SEQ ID NO: 20: CTC conjugated with 10 glutamic acids (CTC_peg 10_e10).

SEQ ID NO: 21: CTC conjugated with 10 glutamic acids (CTC_MP4_e10).

SEQ ID NO: 22: P15 conjugated with 10 glutamic acids (P15).

SEQ ID NO: 23: P15 conjugated with 10 glutamic acids (P15_mp4_e10).

SEQ ID NO: 24: DGEA conjugated with 10 glutamic acids (DGEA_mp4_e10).

SEQ ID NO: 25: ITGA conjugated with 10 glutamic acids (ITGA5).

SEQ ID NO: 26: IKVAV conjugated with 10 glutamic acids (IKVAV_mp4_e10).

SEQ ID NO: 27: LN2 conjugated with 10 glutamic acids (LN2_P3_mp4_e10).

SEQ ID NO: 28: PHSRN conjugated with 10 glutamic acids (PHSRN_mp4_e10).

SEQ ID NO: 29: P3 conjugated with 10 glutamic acids (P3_mp4_e10).

SEQ ID NO: 30: SPARC conjugated with 10 glutamic acids (SPARC 113_mp4_e10).

SEQ ID NO: 31: CBM(1-19)-D10 collagen binding motif.

SEQ ID NO: 32: CBD conjugated with 10 glutamic acids (CBD_MP4_e10).

SEQ ID NO: 33: Targeting group consisting of a polypeptide, DDDDDDDDDD.

SEQ ID NO: 34: Targeting group consisting of a polypeptide, EEEEEEEEEE.

DETAILED DESCRIPTION

While the concepts of the present disclosure are illustrated and described in detail in the figures and the description herein, results in the figures and their description are to be considered as examples and not restrictive in character; it being understood that only the illustrative embodiments are shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

Unless defined otherwise, the scientific and technology nomenclatures have the same meaning as commonly understood by a person in the ordinary skill in the art pertaining to this disclosure.

Aspects of the fracture targeted technology disclosed herein can help both civilians and military personnel. Bone fractures occur at an annual rate of 2.4 per 100 people and cost the US healthcare system approximately $28 billion per year. Of the 6.3 million bone fractures that occur annually in the US, 300,000 result in delayed union or non-union healing. Approximately 887,679 hospitalizations result each year from fractures. Over half (57%) of fractures resulting in hospitalizations occur in persons aged 65 and over. Estimated health care costs are indicated in Table 1, below.

TABLE 1 Cost without Cost with Fracture Healing time surgery surgery Leg 10-12 weeks) $2,500 $16,000 Hip 12+ weeks $11,500  $66,500 Vertebral (8+ weeks) $5,000-15,000 $50,000-150,000 Arm 6-10 weeks $2,500 $16,000

Currently, a substantial fraction of national defense outlays is devoted to combat-related medical expenditures, with a significant proportion of these costs devoted to treatment of orthopedic injuries. Indeed, 65% of all wounds associated with military conflicts since WWI have included orthopedic injuries, and 26% of all injuries to an extremity have involved one or more broken bones. Treatment of bone fractures not only removes a soldier from service for an extended period of time, but also requires the attention of multiple additional personnel to treat, monitor and rehabilitate the injured soldier. Unfortunately, some orthopedic injuries are so severe that resolution of the damage never occurs, and the armed services are then obligated to care for the damaged combatant in perpetuity.

Fractured bones are not only an adverse consequence of combat, they also constitute a prominent repercussion of military training exercises. During the course of a soldier's schooling, a female recruit will have a 3.4-21% chance of suffering a stress fracture, while a male recruit will have a 1-7.9% probability of experiencing the same injury. While such maladies may at first seem trivial, statistics reveal that they cost the military ˜$34,000 per soldier which totals up to ˜$100 million in aggregate per year. Not surprisingly, many affected recruits eventually leave the military as a consequence of their stress fracture, which results in further expenses arising from wasted recruiting and training efforts. Therapies for fractured bones both within and outside of the military rely almost exclusively on mechanical stabilization of the damaged bone (i.e. use of a cast, pin, rod, or plate, etc.). In fact, the only FDA-approved drug for enhancing fracture repair is a bone anabolic agent that must be applied topically to the fracture surface during surgery. Needless to say, such a therapy is inappropriate when the surgery is not otherwise indicated, can only be administered once (i.e. during the brief period when the fracture surface is exposed), cannot be easily adapted for treatment of multiple fractures, and is never used for therapy of stress fractures. What is critically needed is obviously a systemically administered bone anabolic agent (i.e. as drug that can stimulate rapid bone fracture healing) that will concentrate selectively on the bone fracture surface and induce accelerated bone formation only at the damaged site. Surprisingly, nothing of this sort has ever been described in the literature.

Recognizing the enormous need for a systemically administered bone fracture-targeted healing agent, peptides and other molecules with structures that home specifically to bone fracture surfaces following intravenous or subcutaneous administration were identified. A second group of bone anabolic agents (for example, both bone growth stimulating hormones and cytokines as well as various low molecular weight bone growth-inducing drugs, etc.), that when linked to one of our bone fracture-homing peptides, would promote accelerated fracture repair, were also identified. Fortunately, several fracture-targeted bone anabolic drugs met all initial requirements for advancement into large animal studies. That is, the targeted conjugates were found to: i) reduce the time for fractured femur repair in mice by roughly half, ii) induce no detectable systemic toxicity at its effective dose, iii) cause no ectopic bone formation at either the injection site or elsewhere), iv) lead to regeneration of bone at the fracture site that was biomechanically stronger than the contralateral (unbroken) femur, and v) result in eventual remodeling of the fractured region into normal cortical bone.

All in vivo data included herein are from Swiss Webster mice. All mice received an osteotomy on their right femur and received subcutaneous drug administration daily for either 2,3 or 4 weeks, or 17 days, as indicated, for each compound. 1× concentration represents 1 nmol/day, 10× represents 10 nmol/day, 100× represents 100 nmol/day most studies have an n of 5.

Aspects of the disclosure include conjugates sometimes written in the form of X-Y-Z, wherein each conjugate includes at least one moiety (X) that has the ability to effect bone growth, development, and/or healing, for example, anabolic agents, and a targeting moiety (Z) which has an affinity for bone and helps to direct the conjugate to bone. In some of these conjugates, the X and Z portions are joined together by a linker region (Y).

Targeting moieties (Z), many of which are explicit or implicit disclosed herein, have the potential to target bone anabolic agents to bone fractures, ostectomies, and osteotomy sites. The compounds described here are composed of molecules with high affinity towards hydroxyapatite and a bone anabolic agent. Although targeting has been exemplified primarily with acidic oligopeptides, all molecules with affinity towards hydroxyapatite could be attached to a bone anabolic agent to improve fracture repair. These molecules include but are not limited to ranelate, bisphosphonates, tetracyclines, polyphosphates, molecules with multiple carboxylic acids, calcium chelating molecules, metal chelators, acidic amino acid chains of either d or L chirality. Each of the previously listed targeting molecules can be single units, polymers, dendrimers or multiple units. Other molecules can also be substituted for the targeting agent. These include peptides, proteins and manmade molecules that intercalate, bind to, adsorb to, or hybridize with: collagen, the extracellular matrix, heparan sulfate, chondroitin sulfate, keratan sulfate, hyaluronic acid, elastin, fibronectin, laminin, proteoglycans, basement membrane, extracellular polymeric substances, integrins, blood clotting factors, fibrinogen, thrombin, fibrin, and other extracellular macromolecules. It is also possible to target using a combination of the listed targeting molecules.

Definitions

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure pertains.

The term “BV/TV” means the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus.

The term “TbTh” means the trabecular thickness of the 100 thickest micro CT slices of the fracture callus.

The term “BV” means the overall bone volume of the 100 thickest micro CT slices of the fracture callus.

The term “TbSp” means the spacing between the trabecula in the 100 thickest micro CT slices of the fracture callus.

The term “Peak Load” means a postmortem 4 point bend of the healed femur. Peak load represents the maximum force the healed femur withstood before it refractured.

The term “D10” at the end of any name represents that the peptide is targeted to bone by a chain of 10 aspartic acids. D10 can be at the N-terminus or C-terminus of the specified peptide.

The term “E10” or “(D)E10” at the end of any name represents that the peptide is targeted to bone by a chain of 10 (D) glutamic acids.

The term “P4” means a fragment that represents the knuckle epitope in hBMP-2.

The term “P-4” corresponds to residues 73-92 of BMP-2 in which Cys-78, Cys-79, and Met-89 are changed to Serine (Ser), Ser, and Threonine (Thr). BMPs are well known regulators of bone and cartilage formation. BMPs bind as dimers to type I and type II Ser/Thr receptor kinases, forming an oligomeric complex that activates intracellular Smad proteins leading to their translocation into the nucleus where they serve as transcription factors to activate different OB differentiation markers (such as Runx2 (transcription factor for osteoblast differentiation)), leading to osteoblastogenesis. BMPs have also been shown to stimulate mesenchymal stem cells (MSC) differentiation to OBs by promoting recruitment of osteoprogenitor cells.

The term “AHX” in the middle of any name represents that the therapeutic is linked to the targeting peptide via a polymer of 6-(amino)hexanoic acid.

The term “AHX3” in the middle of any name represents that the therapeutic is linked to the targeting peptide via a polymer of (6-(amino)hexanoic acid)₃.

The term “mp4” in the middle of any name represents that the therapeutic is linked to the targeting peptide via a polymer of 4 minipegs as known as 8-Amino-3,6-Dioxaoctanoic Acid.

The term “STB” at the end of any name represents that the compound represents a chemically more stable version of its natural version.

The term “peg10” in the middle of any name represents that the therapeutic is linked to the targeting peptide via a polymer of polyethylene glycol 10.

The term “DAPD” at the end of a compound denotes that the compound has been cyclized via a lactam bridge between diaminopropionic acid (DAP) and aspartic acid (D).

The term “DAPE” at the end of a compound denotes that the compound has been cyclized via a lactam bridge between diaminopropionic acid (DAP) and glutamic acid (E).

The term “KD” at the end of a compound denotes that the compound has been cyclized via a lactam bridge between—Lysine (K)-Aspartic acid (D).

The term “KE” at the end of a compound denotes that the compound has been cyclized via a lactam bridge between—Lysine (K)-Glutamic acid (E).

The term “Cys” at the end of a compound denotes that the compound has a disulfide bridge made by two cysteines.

Compounds which effect bone growth and may be used to practice aspects of the present disclosure include but are not limited to the following: extracellular matrix proteins, fragments of extracellular matrix components, or synthetic peptides or small molecules that mimic the action of extracellular matrix component. Examples of which may include but are not limited to: integrin alpha (ITGA), integrin beta(ITGB), very late antigen(VLA), Fibrinogen receptor, fibronectin, collagen, the extracellular matrix, heparan sulfate, chondroitin sulfate, keratan sulfate, hyaluronic acid, elastin, laminin, proteoglycans, basement membrane, extracellular polymeric substances, integrins, blood clotting factors, fibrinogen, thrombin, fibrin, Cell adhesion molecules (CAMs), integrins, immunoglobulin superfamily (IgSF) CAMs, Selectins, E-selectin, L-selectin, P-selectin, N-CAM (Myelin protein zero), ICAM (1, 5), VCAM-1, PE-CAM, L1-CAM, Nectin(PVRL1, PVRL2, PVRL3), Integrins, LFA-1 (CD11a+CD18), Integrin alphaXbeta2(CD11c+CD18), Macrophage-1 antigen(CD11b+CD18), VLA-4 (CD49d+CD29), Glycoprotein IIB/IIIa(ITGA2B+ITGB3), ITGB1, ITGA7, ITGAV, CD51, Vitronectin(VNRA), MSK8, ITGA2B, CD41, ITGAX, CD11c, ITGA7, FLJ25220, ITGA8, ITGA9, RLC, ITGA10, ITGA11, HsT18964, ITGAD, CD11D, FLJ39841, ITGAE, CD103, HUMINAE, ITGAL, CD11a, LFA1A, ITGAM, CD11b, Macrophage Antigen(MAC), MAC-1, ITGA1, CD49a, VLA1, ITGA2, CD49b, VLA2, ITGA3, CD49c, VLA3, ITGA4, CD49d, VLA4, ITGA5, CD49e, VLA5, ITGA6, CD49f, VLA6, CD29, FNRB, MSK12, MDF2, ITGB2, CD18, LFA-1, MAC-1, MFI7, ITGB3, CD61, GP3A, GPIIIa, ITGB4, CD104, ITGB5, ITGB5, FLJ26658, ITGB6, ITGB6, ITGB7, ITGB8, ITGB8, α1β1, α2β1, α3β1, α4β1, α5β1, α6β1, α7β1, βLβ2, αMβ2, Cadherin (CDH), CDH1, CDH2, CDH12, CDH3, Desmoglein, Desmocollin, Protocadherins, CDH4-R-cadherin (retinal), CDH5, CDH6, CDH7, CDH8, CDH9, CDH10, CDH11, CDH13, CDH15, CDH16, CDH17, CDH18, CDH19, CDH20, CDH23, CDH22, CDH24, CDH26, CDH28, cadherin EGF LAG seven-pass G-type receptor 1(CELSR1), CELSR2, CELSR3, CLSTN1, CLSTN2, CLSTN3, dachsous homolog 1(DCHS1), DCHS2, LOC389118, PCLKC, RESDA, RET, αIIbβ3, αVβ1, αVβ3, αVβ5, αVβ6, αVβ8, α6β4, Desmoglein(DSG), DSG1, DSG2, DSG3, DSG4, Desmocollin(DSC), DSC1, DSC2, DSC3, CD22, CD24, CD44, CD146, CD164, perlecan, agrin, collagen XVIII, collagen type I, collagen type II, collagen type III, collagen type IV, collagen type V, collagen type VI, collagen type VII, collagen type VIII, collagen type IX, collagen type X, collagen type XI, collagen type XII, collagen type XIII, collagen type XIV, collagen type XV, collagen type XVI, collagen type XVII, collagen type XVIII, collagen type XIX, collagen type XX, collagen type XXI, collagen type XXII, collagen type XXIII, collagen type XXIV, collagen type XXV, collagen type XXVI, collagen type XXVII, collagen type XXVIII, collagen type XXIX, Notch II, Notch I, osteopontin, osteonectin, bone sialoprotein, Osteoprotegerin, osteocrin, osteocalcin, matrix extracellular phosphoglycoprotein(MEPE), AC-100, SPARC 113, Sparc 118, CBM, ODP, IKVAV, ITGA5, RRETAWA, YIGSR, PHSRN, RGD, CTC, BCSP, DGEA, GFOGER, KRSR, pRGD, hBSP278-293, heparin binding domain of bone sialoprotein, or CB.

Bone Growth Modifiers and Delivery Peptides

(SEQ ID NO: 1) BFP1D10 DDDDDDDDDDGQGFSYPYKAVFSTQ

BFP (bone forming Peptide) a fragment of immature BMP7 is a 15-amino acid peptide corresponding to residues 100-115 of the immature form of BMP-7 which like BMP2 is involved in osteogenic differentiation, proliferation, and formation of new bone. This short peptide also induces osteogenesis calcium content in MSCs.

BMP-9

BMP-9 is also a potent regulator of osteogenesis and chondrogenesis and is a potent inducer of differentiation of osteoblasts. pBMP9 is a 23-residue peptide derived from residues 68-87 of the knuckle epitope of human BMP-9. The mechanism of action of this peptide is likely to involve the small mothers against decapentaplegic (Smad) pathway. The structure of BMP9 is depicted in FIG. 27.

Ghrelin D10

Ghrelin is a 28-residue peptide hormone synthesized primarily by the gastric fundus in response to fasting, and acts as a ligand of the growth hormone secretagogue (GHS) receptor (GHSR) to promote growth hormone release from the pituitary. Ghrelin stimulation at the GHSR leads to the proliferation of osteoblasts and prevents the apoptosis of osteoblasts through mitogen-activated protein kinase/extracellular signal-regulated kinases (MAPK/ERK) and phosphoinositide 3-kinase/protein kinase B (PKB) (PI3K/AKT) pathways. Ghrelin also stimulates osteoprotegerin (OPG) gene expression, which inhibits the coupling between the osteoclasts and osteoblasts, leading to reduced osteoblast-related osteoclast differentiation. Increased OPG also and decreases osteoclast activity. Ghrelin is only active when the Ser-3 is acylated with octanoic acid. Our construct contains a stabilized version of this where Ser-3 was replaced with diaminopropionic acid. The structure of Ghrelin D10 is depicted in FIG. 28.

Preptin D10

Preptin is a 34-residue peptide hormone that is secreted by the β-cells of the pancreatic islets. This peptide corresponds to Asp-69 to Leu-102 of the E-peptide of proinsulin-like growth factor-II (pro-IGF-II). Preptin's anabolic effects on bone are exerted through its ability to stimulating osteoblasts s proliferation, differentiation, and promoting their survival. Preptin's proliferative effect is predicted to be facilitated through a G-protein-coupled receptor triggering phosphorylation of p42/44 MAP kinases. Some of preptin's anabolic effects are believed to be due to it stimulating an increase in a known bone anabolic connective tissue growth factor. While the native peptide effects glucose metabolism the first 16 amino acids are important for its anabolic effects and have no effects on glucose metabolism. The structure of Preptin D10 is depicted in FIG. 29.

CNP-D10 is a C-Type Natriuretic Peptide Targeted with D10

C-Type Natriuretic Peptide (CNP) contains 22 residues stabilized by an intramolecular disulfide linkage between Cys-6 and Cys-22 it functions as a local regulator of vascular tone, possibly due to its strong vasorelaxant properties. CNP also acts on the differentiation and proliferation of OBs, OCs, and chondrocytes via an autocrine/paracrine process through binding to the natriuretic peptide receptor B (NPR-B). CNP activates bone turnover and remodeling. Endochondral ossification is another mechanism of bone formation affecting chondrocytes. It involves the conversion of an initial cartilage template into bone such as long bones and vertebrae. CNP has been shown to be an important anabolic regulator of endochondral ossification. The structure of CNP-D10 is depicted in FIG. 30.

VIP D10 is Vasoactive Intestinal Peptide Targeted with D10

Vasoactive intestinal peptide (VIP), a neuropeptide that consists of 28 amino acids and originally isolated from porcine intestine. VIP has several effects however its receptors are present on the nerves that rapidly innervate the fracture callus. It has been shown to be an important regulator of bone formation. VIP exerts its biological effects through the G-protein-coupled receptors (VPAC1, VPAC2, and PAC1). Signaling through these receptors also enhanced cell osteoblast differentiation and proliferation. It also increases expressions of collagen type I, osterix, and alkaline phosphatase (ALP) through signaling at the VPAC2 receptor by triggering an increase in intracellular calcium. VIP also increases the expressions of BMPs and the nuclear presence of Smad1 transcription factor, which can activate various bone-specific genes. VIP also enhances osteoblast proliferation and mineralization through increased gap junction intercellular communication (GJIC) between osteoblasts. VIP also affects the differentiation of osteoclasts thus leading to an increase in bone resorption. The structure of VIP D10 is depicted in FIG. 31.

Substance P with 4 Mini PEG Conjugated to D10

Substance P- is an 11-amino acid long pro-inflammatory neuropeptide belonging to the tachykinin family. Substance P improves mineralization of osteoblasts and the expression of osteogenic markers at late-stage bone formation, by activating neurokinin-1 receptor, a G-protein coupled receptor found in the central and peripheral nervous systems. Also, substance P reduces osteoclastogenesis and bone resorption. Substance P upregulates the expressions of collagen type 1, ALP, Runx2 and osteocalcin in osteoblasts this effect involves the activation of Wnt/β-catenin signaling pathway. Substance P promotes differentiation and migration capability of rat bone marrow MSCs and activates BMP-2 expression in osteoblasts. Some of substance p's anabolic effects are attributed to in human to increases in osteoblast proliferation and mineralization through increased gap junction intercellular communication between osteoblasts. Gap junction intercellular communication has important roles in conveying the anabolic effects of hormones and growth factors and regulating transcription of osteogenic markers. The structure of Substance P with 4 mini PEG conjugated to D10 is depicted in FIG. 32.

CBMD10- is the Collagen Binding Motif of Osteopontin Targeted by D10

CBM-collagen binding motif is the highly conserved 28-residue collagen binding motif (CBM) (residues 150-177) of human osteopontin. Osteopontin, a glycosylated phosphoprotein prominently localized in the extracellular matrix (ECM) of mineralized bone tissue to form a complex with collagen in bone tissue, thereby inducing mineralization of collagen fibrils. CBM enhances osteoblast differentiation of human MSC. CBM causes osteogenic differentiation of human bone marrow MSCs and increases mineralized of bone. CBM works in human MSCs by increasing extracellular Ca²⁺ influx, which leads to the activation of CaMKII and the subsequent phosphorylation of ERK1/2, ultimately influencing OB differentiation. The structure of VIP D10 is depicted in FIG. 33.

ODP D10

Osteopontin-derived peptide (ODP), a 15-residue peptide derived from rat osteopontin. ODP like CBM is a fragment of extracellular protein involved in the mineralization of collagen. ODP enhanced the differentiation and mineralization of MSCs. ODP improves the attachment via receptor mediated attachment and migration of osteoblasts and fibroblasts to the fracture site. ODP improves the proliferation and migration of osteoblasts. Though the signaling pathways aren't completely elucidated for this molecule its believed that it works in a similar mechanism as CBM. The structure of ODPD10 is depicted in FIG. 34.

(SEQ ID NO: 2) OGP-D10 DDDDDDDDDDALKRQGRTLYGFGG

OGP-targeted Osteogenic growth peptide (OGP) is composed of a 14-AA residue identical to the C-terminus of histone 4 conjugated to an acidic oligopeptide at the N-terminus. Systemic administration of free OGP has been shown to improve fracture repair by improving the mineralization of cartilaginous fracture callus.

(SEQ ID NO: 11) MGF-DDDDDDDDDDYQPPSTNKNTKSQRRKGSTFEEHK

Targeted Mechano growth factor (MGF E peptide is a splice variant of insulin-like growth factor I (IGF-I) with a targeting acidic oligopeptide on the N terminus. MGF causes osteoblast proliferation through the MAPK-ERK signaling pathway. Local injections (57 ug/kg) in rabbit bone defects (5 mm) demonstrated accelerated healing through osteoblast proliferation.

(SEQ ID NO: 12) TP508- DDDDDDDDDDAGYKPDEGKRGDACEGDSGGPFV

Targeted TP-508 is a prothrombin peptide that has been modified on the N-terminus with an acidic oligopeptide. The anabolic portion of TP-508 has been used in clinical trials for repairing foot ulcers. Free tp-508 has a proliferative effect on osteoblasts. Local injections have demonstrated accelerated fracture repair in older rats.

Chemotactic Collagen Fragment (CTC) (D)E₁₀

The 12-residue chemotactic cryptic peptide (CTC), derived from the CTX region of collagen type III, has chemotactic activity for a number of human stem cells. CTX is the C-terminal telopeptide that can be used as a biomarker in the serum to measure the rate of bone turnover. In vitro, 0.1 mM CTC increased the expression of osteogenic genes; ALP activity and mineralization of human perivascular stem cells (have properties of MSCs and are able to undergo osteogenesis). In a mouse model of limb amputation, 150 g CTP caused local bone nodule formation after 2 weeks. In addition, it has the ability to alter stem cell recruitment and differentiation at the site of injury. The structure of CTC (D)E₁₀ is depicted in FIG. 35.

P-15 Peptide (Collagen Fragment)

P-15 peptide is a 15-reside peptide corresponding to the sequence 766-780 of the α-1 chain of type I collagen, which is uniquely involved in binding of cells, such as OBs. This peptide mimics the role of collagen in forming collagenous matrices and playing a role in cell adhesion and mineralization. Nguyen et al. fabricated a composite matrix consisting of an organic bone matrix (ABM), which has the same mineral composition as normal human bone, coated with P-15 suspended in hyaluronate hydrogel. Implantation of this composite matrix in vivo led to migration and attachment of host osteoprogenitor cells to this matrix, followed by development of mineralized bone. Other reports also showed the peptide's bone-forming capability when implanted in some form of matrix or another. A systemically adminsterable conjugate has been developed that targets the collagen memetic to sites of damaged bone without the need for invasive surgery. FIG. 42 depicts the structure of P-15.

DGEA (Collagen Fragment)

DGEA is a tetrapeptide corresponding to residues 435-438 of type I collagen. Type 1 collagen is an important component of the extracellular matrix that is involved in cell attachment and regulation. This peptide was shown to induce early osteogenic differentiation of human bone marrow MSCs via binding to the integrin receptor α2β1. In vivo, the peptide increased bone formation the DGEA sequence resulted in enhanced osteogenic differentiation and increased mineral deposition. This positive regulator of bone cell development once localized to the fracture site can assist in creating the correct chemical cue to the mesenchymal stem cells to differentiate into osteoblast to repair the defect. The disclosed construct of DGEA is the full natural 4 amino acids with a Serine and Proline on the C terminus. On the N terminus is 4 minipeg spacers proceeded by ten d glutamic acids. FIG. 50 depicts the structure of DGEA_mp4_e10.

ITGA5

The present disclosure demonstrates that numerous components of the extracellular matrix are anabolic and when delivered to the fracture site can improve fracture repair with virtually no side effects. One of the most promising compounds is ITGA5 a synthetic integrin alpha 5 ligand. Integrin alpha 5 is high expressed on mesenchymal stem cells as they transition from stem cell to osteoblast. ITGA5 natural ligand is fibronectin. But ITGA5 or CRRETAWACITGA 5 was discovered via phage display and has a high affinity to just ITGA5. ITGA5 is a cyclic 9 amino acids that can be cyclized with a stable amide bond. Targeted delivery of ITGA5 has shown impressive anabolic effects so far in repeated experiments. Peptide-mediated activation of ITGA5 in murine C3H10T1/2 mesenchymal cells in the literature resulted in the generation of the integrin-mediated cell signals FAK and ERK1/2-MAPKs. It has been shown that, peptide-based activation of ITGA5 protected from cell apoptosis but did not affect cell adhesion or replication, while it enhanced the expression of the osteoblast marker genes Runx2 and type I collagen and increased extracellular matrix (ECM) mineralization anabolic effect resulted from decreased cell apoptosis and increased bone forming surfaces and bone formation rate (BFR). It has been shown that pharmacological activation of ITGA5 in mesenchymal cells is effective in promoting de novo bone formation as a result of increased osteoprogenitor cell differentiation into osteoblasts and increased cell protection from apoptosis. Some of ITGAs effect is potentially through Wnt-β-catenin signaling to promote osteoblast as mediated via signals FAK and ERK1/2-MAPKs. FIG. 55 depicts the structure of ITGA5. FIG. 67 depicts the structure of ITGA_mp4_e10_DAPE. FIG. 65 depicts a structure with a stabilized ring of ITGA, which can be created by substituting the 2 cystines for lysine and glutamic acid and forming a stabilized amide bone between their side chain. FIG. 72 depicts the structure of ITGA_mp4_e10_DAPD. FIG. 77 depicts the structure of ITGA_mp4_e10_KD. FIG. 82 depicts the structure of ITGA_mp4_e10_KE.

IKVAV

IKVAV is a laminin α1 which is a 400 kd chain of lamanin the large glycoprotein that makes up the majority of the basement membrane of the extracellular matrix. Lamanins contribute to cell differentiation, cell shape and movement, maintenance of tissue phenotypes, and promotion of tissue survivaLT IKAV derived from the largest of the chains of lamanin has been found to drives osteogenic differentiation of human MSCs. IKVAV induces Runx2 and ALP expression in human MSCs promotes osteogenesis by integrin signaling. This is due to the fact that IKVAV the activation of a range of integrins: a3b1, a4b1, and a6b1 that are expressed on human mesenchymal stem cells as they undergo the transition to osteoblasts. By targeting Ikvav to the fracture callus we can create a stimulatory environment which differentiates the periosteal stem cells into osteoblasts to promote a more anabolic repair response. Ikvav e10 also improves cell adhesion at the damaged site. The osteogenic genes induction of Ikvav and other related integrin binding peptides is facilitated via the formation of a focal adhesion. Focal adhesions mediate intracellular changes beyond just serving as attachment point for the cytoskeleton to the extracellular matrix via the recruitment of proteins such as focal adhesion kinase (FAK), Rho (family of GTPases that regulates cellular function), Rac (a subfamily of the Pho family of GTPases), and integrin-linked kinase (ILK), are also recruited. The function of the proteins includes both regulation of cytoskeletal remodeling and the assembly or disassembly of the focal adhesion complex, but they also tie into intracellular signaling cascades, such as mitogen-activated protein kinase and C-Jun N-terminal kinase (INK). These signaling cascades induce the change in expression of osteogenic genes such as Runx2 and ALP. FIG. 87 depicts the structure of IKVAV_mp4_e10.

LN2_P3 (Laminin)

Laminin in a major protein comment of the extracellular matrix. They primarily mediate cell attachment to surfaces either via syndecans or integrins. Human laminin a2 LG1 domain mediates cell attachment through syndecan-1 by inducing phosphorylation and membrane localization of protein kinase Cd. LN2_P3 or DLTIDDSYWYRI is one of the bioactive cores of human laminin a2 chain. It has been shown to accelerate osteointegration of dental implants and overall to improve cell attachment and activate osteoblasts. The conjugate of the present disclosure localized the LN2_p3 motif via an N terminally attached minipeg 4 spacer and targeting ligand. FIG. 92 depicts the structure of LN2_P3_mp4_e10.

PHSRN (Fibronectin)

Fibronectin (FN) is a predominant ECM protein that mediates the adhesion and spreading of many cell types. Its interactions with cells mediate and controls, migration, survival and activation. RGD is the most well studied binding motif form fibronectin. But fibronectin contains another cell attachment motif PHSRN. The peptide PHSRN is found in the 9th type III domain of FN, adjacent to the 10th domain that contains the RGD peptide. Like RGD PHSRN interacts with the Alpha5Beta1 and AlphaIIbBeta31 Integrin receptors. Through these cellular interactions it mediates not only cell attachment but initiates an increase in the activity of the cells. It has been shown that PHSRN improves the attachment and activity of osteoblasts. The conjugate of the present disclosure chemically homes PHSRN to the sight of damaged bone via a (D)e10 targeting ligand attached to PHSRNs N terminus via a minipeg spacer. FIG. 97 depicts the structure of PHSRN_mp4_e10.

P3 (Bone Sialoprotein)

Bone sialoprotein is a very common nonmineral component of bone It is a highly acidic globular protein which plays roles in cell attachment, angiogenesis. One of it more important roles is in the nucleation of hydroxyapatite crystals in newly forming bone. Bone sialoprotein like fibronectin contains the RGD motif (a sequence made up of arginine, glycine, and aspartic acid) which is in evolved in cell attachment and proliferation. P3 which represents residues 278-293 of human bone sialoprotein has been utilized to improve osteointegration by improving cell proliferation and attachment via its interaction the alpha5beta1 and alpha3beta3 ligand receptors RIIbd3 receptors integrin interaction. Rather than having to locally apply it, a targeted construct of the present disclosure has been developed which consists of the P3 fragment followed by a 4 minipeg spacer and 10 (D) glutamic acids to home to bone fractures. FIG. 102 depicts the structure of P3_mp4_e10.

SPARC₁₁₃

SPARC₁₁₃ are fragments of the Secreted Protein Acidic and Rich in Cysteine (SPARC aka osteonectin) which is expressed during development and in wound repair. SPARC is a copper binding protein in the extracellular matrix. SPARC is cleaved by a number of proteases in vivo, which releases domains with a variety of biological effects. SPARC₁₁₃ is residue 113-127 of SPARC and is from released from the follistatin-like domain and contain the tripeptide GHK (a sequence made up of glycine, histidine, and lysine), which promotes angiogenesis in the rabbit cornea assay and accelerates dermal wound healing in mouse and rat models. GHK of SPARC₁₁₃ binds to copper and initiates a vast host of tissue repair including, macrophage chemotaxis, angiogenesis, initiates protein expression of collagen and other growth factors. FIG. 107 depicts the structure of SPARC 113_mp4_e10.

CBM(1-19)-D10 Collagen Binding Motif

CBM(1-19)-D10 collagen binding motif is the truncated version (1-19) of the highly conserved 28-residue collagen binding motif (CBM) (residues 150-177) of human osteopontin. Osteopontin, a glycosylated phosphoprotein prominently localized in the ECM of mineralized bone tissue to form a complex with collagen in bone tissue, thereby inducing mineralization of collagen fibrils. CBM enhances osteoblast differentiation of human MSC. CBM causes osteogenic differentiation of human bone marrow MSCs and increases mineralized of bone. CBM works in human MSCs by increasing extracellular Ca₂₊ influx, which leads to the activation of CaMKII and the subsequent phosphorylation of ERK1/2, ultimately influencing OB differentiation. FIG. 112 depicts the structure of CBM(1-19)-D10 collagen binding motif.

Collagen Binding Domain (CBD) of Osteopontin

Collagen Binding domain (CBD) of osteopontin, which corresponds to residues 35-62 of rat osteopontin, was also shown to stimulate human osteosarcoma cell differentiation into Osteoblasts in vitro (at concentration of 0.01 mM) as determined by increased expression of ALP, and type I collagen after 14 days (FIG. 16).₁ CBD's effect on cell differentiation was shown to involve the activation of MAPK and protein kinase B (Akt) pathways. The conjugate of the present disclosure is 1-28 of osteopontin followed by 4 peg 2 spacers followed by ten d glutamic acids to home it to bone fractures. FIG. 116 depicts the structure of CBD_MP4_e10.

Material and Methods Solid Phase Peptide Synthesis

Unless noted otherwise, the conjugates of the present disclosure are synthesized using the following synthesis. In a solid phase peptide synthesis vial capable of bubbling nitrogen, Wang resin (0.39 mmol/g) was loaded at 0.39 mmol/g with the first amino acid overnight in dichloromethane (DCM) and diisopropyl ethyl amine (DIPEA). The resin was then capped with acetic anhydride and pyridine for 30 minutes, followed by three washes of DCM and dimethylformamide (DMF), respectively. Following each amino acid coupling reaction, fluoroenylmethyloxycarbonyl (Fmoc)-groups were removed by three 10-minute incubations with 20% (v/v) piperidine in DMF. The resin was then washed 3× with DMF prior to the next amino acid being added. Each amino acid was added in a 5-fold excess with N,N,N′N′-Tetramethyl-O-(1H-benzotriazol-1-yl)uronium hexafluorophosphate (HBTU) in DIPEA. Upon completion of the synthesis, peptides were cleaved using 95:2.5:2.5 trifluoroacetic acid:water:triisopropylsilane. Cysteine containing peptides were cleaved using 95:2.5:2.5 trifluoroacetic acid:triisopropylsilane:water: and 10 fold tris(2-carboxyethyl)phosphine (TCEP).

Cyclization Method for Disulfide Bridged Cyclic Peptides

For Amylin(1-8) and CGRP, the standard synthesis of the linear form of the cyclic peptides Fmoc Cystine with Acetamidomethyl protecting group on the sulfur was used. Then, to cyclize the peptide, the Cys(Acm) On-Resin was suspended the linear peptide resin in N,N-dimethylformamide (DMF) (approximately 1 mL/gram of resin). Then, the resin was treated with 10 equiv. of iodine (12) in DMF/H2O 4:1 (v/v), approximately 1 mL/gram of resin). Then, argon gas was bubbled through the reaction mixture at room temperature for 40 minutes. Then, the resin was filtered and washed 3 times with DMF, 2 times with 2% ascorbic acid in DMF, 5 times with DMF, and 3 times with dichloromethane (DCM). Then, proceeded with normal n terminal fmoc deprotection and cleavage from the resin with normal cleavage solution with no TCEP added to preserve the disulfide bond. The peptides were then as all peptides purified using reverse phase chromatography on an IPLC using a 0-50% 20 mM ammonium acetate:acetonitrile gradient. The product was then identified from the appropriate fraction using liquid chromatography/mass spectrometry (LC/MS) and lyophilized to recover it from the water:acetonitrile mixture. All compounds were dissolved in sterile phosphate buffered saline (PBS) at the appropriate dose concentrations for drug delivery.

Cyclization Method for Stabilized Lactam Peptides

For ITGA_mp4_e10_stb, ITGA_mp4_e10_KD, ITGA_mp4_e10_KE, and ITGA_mp4_e10_DAPD, ITGA_mp4_e10_DAPE, the standard synthesis of the linear form of the cyclic peptides Fmoc Glutamic, Asapartic acid, Diaminopropionic, Lysine acid containing with Allyl ethers or allyloxycarbonyl (alloc) protecting group on the carboxylic acid or amine were used at the appropriate points desired for cyclization. Then, the first step was the removal of Allyl Esters and Aloc Groups. This was done by swelling the linear peptide-resin in chloroform (CHCl₃) followed by suspending the swollen resin in CHCl₃ (approximately 35 mL per gram of resin). Then, acetic acid (0.5 mL per gram of resin), N-methylmorpholine (2 mL per gram of resin), and Pd(PPh3)4 (0.3 equivalents based on resin substitution) were added to the resin. Next, the mixture was bubbled at room temperature for 24 hours to remove the allyl ethers and aloc protecting group. Then, the deprotected resin was filter and wash with dichloromethane (DCM). The deprotected amino acids were then coupled onto the resin by suspending the resin in Dimethyl formamide(DMF). Then, they were coupled with 3 equivalents of benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate, 3 equivalents of 6-Chloro-1-hydroxybenzotriazole dihydrate, 3 equivalents of N,N-Diisopropylethylamine for 24 hours. Next, it was washed with 3 times with DMF, 3 times with DCM, 2 times with methanol, and then dried with argon gas. Then, the resin was subjected to normal cleavage conditions as previously described. The peptides were then as all peptides purified using reverse phase chromatography on an HPLC using a 0-50% 20 mM ammonium acetate:acetonitrile gradient. The product was then identified from the appropriate fraction using LCMS and lyophilized to recover it from the water:acetonitrile mixture. All compounds were dissolved in sterile PBS at the appropriate dose concentrations for drug delivery.

General Methods for Obtaining Test Data

The targeted conjugates were synthesized using standard Fmoc solid-phase peptide synthesis, as described above. To ensure the conjugates' activity, mouse pre-osteoblast (MCTC3-E1) cells were treated with the targeted and untargeted compounds for three days at concentrations from 1 pM to 100 nM. After three days of treatment, the cells were harvested, and the RNA was purified from the cells. Expression levels of ALP, RUNx2 (transcription factor for osteoblast differentiation), osterix (OSX), osteopontin (OPN), collagen 1A (Col-1A), OPG, RANKL, sclerostin gene (SOST), and OC were quantified via quantitative reverse transcription polymerase chain reaction (RT-qPCR). Once the biological activity of the conjugates was confirmed, they were tested in vivo in a fracture model. Aseptic surgical techniques were used to place a 23-gage needle as in intramedullary nail in the femur of anesthetized, 12-week-old Swiss Webster mice for internal fixation before fracture. Femur fractures were induced using a drop weight fracture device from RISystem. The mice received buprenorphine for three days post fracture. The mice were dosed subcutaneously each day for three weeks or 17 days. Fracture healing was assessed using microCT (Scanco Medical Ag). Morphometric parameters were quantified in the 100 widest slices of the fracture callus. Trabecular thickness (Tb.Th.), trabecular spacing (Tb.Sp.), total volume (TV), and volume of calcified callus (BV) were calculated. Fractured femurs were tested for strength in a four-point bend to failure using an Electro Force TestBench (TA Instruments). Lower supports were 10 mm apart on the anterior face of the femur in contact with the proximal and distal diaphysis. Upper supports were 4 mm apart and spanned the entire fracture callus on the diaphysis. Force was applied from the posterior face of the femur with a displacement rate of 0.3 mm/sec. Peak load, yield load, stiffness, displacement post yield, work to fracture, and deformation data were generated. Statistical analysis was performed using a two-way analysis of variance (ANOVA) and a Tukey post-hoc analysis with significance reported at the 95% confidence level. All animal experiments were performed in accordance with protocols approved by Purdue University's Institutional Animal Care and Use Committee (IACUC).

EXAMPLES Example 1. Targeted Delivery of Src Kinase Inhibitors to Fracture Site for Accelerated Healing

Example 1 shows representative Src kinase inhibitors Dasatinib and E738 (structures shown in FIGS. 3-4 respectively) effectively increased the bone density of the fracture callus when they are conjugated with acidic aspartic acids. See FIGS. 1-2, where bone density of the fracture callus from the targeted Dasatinib group is twice as dense as the saline group, and 50% denser than the free Dasatinib group; targeted E738 conjugate has significantly improved the bone density and trabecular thickness at the fracture callus. The structure of CBMD10 is depicted in FIG. 33.

Example 2. Representative Anabolic Peptides on Peak Load of Fractured Femurs after Two Weeks

Example 2 provides the maximum force a representative anabolic peptide induced healed femur can withstand before it refractured. As shown in FIG. 5, bone morphogenetic protein pathway signaling peptide BFP-D10 with 100 nmol/day (100×) treatment obtained the maximum peak load, followed by IGF derived peptide of Preptin-D10 100×, and Osteogenic growth peptide (OGP-D10 100×), as compared to PBS.

Example 3. Preptin D10 Efficacy on Fracture Healing

Example 3 indicates Preptin D10 effect on healing fractured bone after 2 weeks of various concentrations application (1 nmol/day, 10 nmol/day and 100 nmol/day, referred as 1×, 10× and 100× respectively). The healing was reflected as BV/TV in FIG. 6, TbTh in FIG. 7 and bone volume in FIG. 8, all in a dose dependent manner.

Example 4. OGP D10 Efficacy on Fracture Healing

Example 4 indicates osteogenic growth peptide conjugate (OGP-D10) effect on healing fractured bone after 2 weeks of various concentrations application (1 nmol/day, and 100 nmol/day, referred as 1×, and 100× respectively). The healing was reflected as BV/TV in FIG. 9, TbTh in FIG. 10 and TbSp in FIG. 11, all in a dose dependent manner.

Example 5. BFP D10 Efficacy on Fracture Healing

Example 5 indicates bone forming peptide conjugate (BMP-D10) effect on healing fractured bone after 2 weeks of various concentrations application (1 nmol/day, 10 nmol/day and 100 nmol/day, referred as 1×, 10× and 100× respectively). The healing was reflected as BV/TV in FIG. 12, and TbSp in FIG. 13 in a dose dependent manner.

Example 6. Substance P D10 Effect on Fracture Healing

Example 6 indicates substance P D10 conjugate effect on healing fractured bone after 4 weeks of various concentrations application (1 nmol/day, 10 nmol/day and 100 nmol/day, referred as 1×, 10× and 100× respectively). The healing was reflected as BV/TV in FIG. 14A in dose dependent manner. FIG. 14B indicates the peak load of substance P D10 0× induced healed femur can withstand between 30-35 Newtons force.

Example 7. Ghrelin-D10 Effect on Fracture Healing

Example 7 indicates Ghrelin-D10 conjugate effect on healing fractured bone after 4 weeks of various concentrations application (nmol/day, 10 nmol/day and 100 nmol/day, referred as 1×, 10× and 100× respectively). The healing was reflected as BV/TV in FIG. 15 in dose dependent manner.

Example 8. pBMP9 D10 Effect on Fracture Healing

Example 8 indicates pBMP9 D10 conjugate effect on healing fractured bone after 4 weeks of various concentrations application (nmol/day, 10 nmol/day and 100 nmol/day, referred as 1×, 10× and 100× respectively). The healing was reflected as bone volume in FIG. 16 and BV/TV in FIG. 17 in a dose dependent manner.

Example 9. CNP D10 Effect on Fracture Healing

Example 9 indicates C-Type Natriuretic Peptide conjugate CNP D10 effect on healing fractured bone after 4 weeks of various concentrations application (1 nmol/day and 10 nmol/day referred as 1× and 10× respectively). The healing was reflected as BV/TV in FIG. 18 in a dose dependent manner.

Example 10. ODP D10 Effect on Fracture Healing

Example 10 indicates osteopontin derived peptide conjugate ODP D10 effect on healing fractured bone after 4 weeks of 1 nmol/day (referred as 1×). The healing was reflected as BV/TV in FIG. 19.

Example 11. CBM D10 Effect on Fracture Healing

Example 11 indicates collagen binding motif of osteopontin conjugate CBM D10 effect on healing fractured bone after 3 weeks of various concentrations application (0.1 nmol/day, 1 nmol/day and 10 nmol/day, referred as 0.1×, 1× and 10× respectively). The healing was reflected as BV/TV in FIG. 20 in a dose dependent manner. It is worth noting that the lowest does of CBM D10 has the similar effect of free PTH, an anabolic drug without specific bone targeting.

Example 12. P4 D10 Effect on Fracture Healing

Example 12 indicates P4 D10 conjugate effect on healing fractured bone after 4 weeks of various concentrations application (nmol/day and 10 nmol/day, referred as 1× and 10× respectively). The healing was reflected as BV/TV in FIG. 21 in a dose dependent manner and bone volume in FIG. 22.

Example 13. MGF D10 Effect on Fracture Healing

Example 13 indicates mechano growth factor conjugate MGF D10 effect on healing fractured bone after 4 weeks of various concentrations application (1 nmol/day and 10 nmol/day, referred as 1× and 10× respectively). The healing was reflected as BV/TV in FIG. 23 in a dose dependent manner.

Example 14. TP508 D10 Effect on Fracture Healing

Example 14 indicates thrombin fragment TP508 conjugate TP508 D10 effect on healing fracture after 4 weeks of various concentrations application (1 nmol/day and 10 nmol/day, referred as 1× and 10× respectively). The healing was reflected as BV/TV in FIG. 24 in a dose dependent manner.

Example 15. VIP D10 Effect on Fracture Healing

Example 15 indicates vasoactive intestinal peptide conjugate VIP D10 effect on healing fracture after 4 weeks of 1 nmol/day application (1×). The healing was reflected as BV/TV in FIG. 25 and TbTh in FIG. 26.

Example 16. Chemotactic Collagen Fragment(CTC) (D)E10

Example 16 indicates CTC (D)E₁₀ conjugate effect on healing fractures. FIG. 36 depicts in vivo fracture healing efficacy of CTC_peg10_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1×, 1×, and 10× are respectively 1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. CTC_peg10_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 37 depicts in vivo fracture healing efficacy of CTC_peg10_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CTC_peg10_(D)E₁₀ conjugate improves bone strength at the fracture calluses three weeks post fracture.

FIG. 38 depicts the structure of CTC_MP4_e10. FIG. 39 depicts in vivo fracture healing efficacy of CTC_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. CTC_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 40 depicts in vivo fracture healing efficacy of CTC_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. CTC_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 41 depicts in vivo fracture healing efficacy of CTC_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. CTC_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

Example 17. P-15 (Collagen Fragment)

Example 17 indicates P-15 conjugate effect on healing fractures. FIG. 43 depicts in vivo fracture healing efficacy of P-15_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1×, 1×, and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. The P-15_(D)E10 conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 44 depicts in vivo fracture healing efficacy of P-15_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. The P-15_(D)E10 conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 45 depicts the structure of P-15_mp4_e10, a P15 fragment connect via 4 peg2 spacers to (D)E10 bone targeting ligand. The linker gives it the space it needs to interact with neighboring cells.

FIG. 46 depicts in vivo fracture healing efficacy of P-15_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P-15_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 47 depicts in vivo fracture healing efficacy of P-15_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P-15_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 48 depicts in vivo fracture healing efficacy of P-15_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P-15_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 49 depicts in vivo fracture healing efficacy of P-15_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P-15_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

Example 18. DGEA (Collagen Fragment)

Example 18 indicates DGEA conjugate effect on healing fractures. FIG. 51 depicts in vivo fracture healing efficacy of DGEA_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. DGEA_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 52 depicts in vivo fracture healing efficacy of DGEA_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. DGEA_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 53 depicts in vivo fracture healing efficacy of DGEA_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. DGEA_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 54 depicts in vivo fracture healing efficacy of DGEA_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. DGEA_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

Example 19. ITGA5

Example 19 indicates ITGA5 conjugates effect on healing fractures. FIG. 56 depicts In vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 57 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 58 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=10) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 1× and 10× are respectively 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 59 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 60 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 61 depicts in vivo fracture healing efficacy of of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Tbth—represents The trabecular thickness of the 100 thickest micro CT slices of the fracture callus and is a measure the quality of the bone at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. The of ITGA_mp4_(D)E₁₀_Cys conjugate raises bone quality at the fracture calluses three weeks post fracture.

FIG. 62 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Stiffness represents the Youngs modulus of the healed femur as it was measured before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how stiff the bone is at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. The of ITGA_mp4_(D)E₁₀_Cys conjugate raises bone stiffness at the fracture calluses three weeks post fracture.

FIG. 63 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 64 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Cys conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1×, 1× and 10× are respectively 0.1 nmol, 1 nmol, and 10 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Cys conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 66a depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Stb(stable) conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 1×, 1× and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Stb conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 66b depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_Stb(stable) conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/tv represents the bone volume of the total volume of 100 thickest micro CT slices of the fracture callus and is a measure of bone density at the site of fracture repair. 1×, 10× and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_Stb conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 68 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPE conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 69 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPE conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 70 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPE conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 71 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPE raises bone strength at the fracture calluses three weeks post fracture.

FIG. 73 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPD conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 74 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPD conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 75 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPD conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 76 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPE raises bone strength at the fracture calluses three weeks post fracture.

FIG. 78 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KD conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 79 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KD conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 80 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_DAPD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_DAPD conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 81 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KD conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KD raises bone strength at the fracture calluses three weeks post fracture.

FIG. 83 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KE conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 84 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KE conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 85 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KE conjugate raises bone strength at the fracture calluses three weeks post fracture

FIG. 86 depicts in vivo fracture healing efficacy of ITGA_mp4_(D)E₁₀_KE conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. ITGA_mp4_(D)E₁₀_KE raises bone strength at the fracture calluses three weeks post fracture.

Example 20. IKVAV (Laminin)

Example 20 indicates IKVAV conjugate effect on healing fractures. FIG. 88 depicts In vivo fracture healing efficacy of Ikvav_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. IKVAV_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses three weeks post fracture.

FIG. 89 depicts in vivo fracture healing efficacy of IKVAV_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. IKVAV_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 90 depicts in vivo fracture healing efficacy of IKVAV_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. IKVAV_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

FIG. 91 depicts in vivo fracture healing efficacy of IKVAV_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. IKVAV_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses three weeks post fracture.

Example 21. LN2 (Laminin)

Example 21 indicates LN2 conjugate effect on healing fractures. FIG. 93 depicts In vivo fracture healing efficacy of LN2_P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. LN2_P3_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses 17 days post fracture.

FIG. 94 depicts in vivo fracture healing efficacy of LN2_P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. Ln2_P3_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses 17 days post fracture.

FIG. 95 depicts in vivo fracture healing efficacy of Ln2_P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. Ln2_P3_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

FIG. 96 depicts in vivo fracture healing efficacy of Ln2_P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. LN2_P3_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

Example 22. PHSRN (Fibronectin)

Example 22 indicates PHSRN conjugate effect on healing fractures. FIG. 98 depicts In vivo fracture healing efficacy of PHSRN_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. PHSRN_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses 17 days post fracture.

FIG. 99 depicts in vivo fracture healing efficacy of PHSRN_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. PHSRN_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses 17 days post fracture.

FIG. 100 depicts in vivo fracture healing efficacy of PHSRN_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. PHSRN_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

FIG. 101 depicts in vivo fracture healing efficacy of PHSRN_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. PHSRN_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

Example 23. P3 (Bone Sialoprotein)

Example 23 indicates P3 conjugate effect on healing fractures. FIG. 103 depicts In vivo fracture healing efficacy of P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P3_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses 17 days post fracture.

FIG. 104 depicts in vivo fracture healing efficacy of P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P3_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses 17 days post fracture.

FIG. 105 depicts in vivo fracture healing efficacy of P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P3_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

FIG. 106 depicts in vivo fracture healing efficacy of P3_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 1 nmol, 10 nmol, and 100 nmol of the conjugate were delivered daily by subcutaneous injection. P3_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

Example 24. SPARC113

Example 24 indicates SPARC₁₁₃ conjugate effect on healing fractures. FIG. 108 depicts In vivo fracture healing efficacy of SPARC113_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV represents the bone volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how much bone has mineralized at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. SPARC113_mp4_(D)E₁₀ conjugate raises bone mineralization at the fracture calluses 17 days post fracture.

FIG. 109 depicts in vivo fracture healing efficacy of SPARC_113_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. SPARC_113_mp4_(D)E₁₀ conjugate raises bone density at the fracture calluses 17 days post fracture.

FIG. 110 depicts in vivo fracture healing efficacy of SPARC_113_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. SPARC_113_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

FIG. 111 depicts in vivo fracture healing efficacy of SPARC_113_mp4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 17 days. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair. 0.1 nmol, 1 nmol, and 10 nmol of the conjugate were delivered daily by subcutaneous injection. SPARC_113_mp4_(D)E₁₀ conjugate raises bone strength at the fracture calluses 17 days post fracture.

Example 25. CBM(1-19)-D10 Collagen Binding Motif

Example 25 indicates CBM(1-19) collagen binding motif effect on healing fractures. FIG. 113 depicts in vivo fracture healing efficacy of CBM(1-19)_D₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV—represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CBM(1-19)_D₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 114 depicts in vivo fracture healing efficacy of CBM(1-19)_D₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Tbth—represents The trabecular thickness of the 100 thickest micro CT slices of the fracture callus and is a measure the quality of the bone at the site of fracture repair. 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CBM(1-19)_D₁₀ conjugate raises bone quality at the fracture calluses three weeks post fracture.

FIG. 115 depicts in vivo fracture healing efficacy of CBM(1-19)_D₁₀ conjugate on Swiss webster fracture-bearing mice (n=5) after 3 weeks. Max load represents the maximum force the healed femur withstood before it refractured in a postmortem 4 point bend analysis. Peak load is a measure of how strong the bone is at the site of fracture repair 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CBM(1-19)_D₁₀ conjugate improves bone strength at the fracture calluses three weeks post fracture.

Example 26. Collagen Binding Domain (CBD) of Osteopontin

Example 26 indicates CBD (D)E₁₀ conjugate effect on healing fractures. FIG. 117 depicts In vivo fracture healing efficacy of CBD_MP4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. BV/TV represents the bone volume divided by total volume of the 100 thickest micro CT slices of the fracture callus and is a measure of how dense the bone is at the site of fracture repair. 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CBD_MP4_(D)E₁₀ conjugate raises bone density at the fracture calluses three weeks post fracture.

FIG. 118 depicts in vivo fracture healing efficacy of CBD_MP4_(D)E₁₀ conjugate on Swiss Webster fracture-bearing mice (n=5) after 3 weeks. Tbth—represents The trabecular thickness of the 100 thickest micro CT slices of the fracture callus and is a measure the quality of the bone at the site of fracture repair. 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The of CBD_MP4_(D)E₁₀ conjugate raises bone quality at the fracture calluses three weeks post fracture.

FIG. 119 depicts in vivo fracture healing efficacy of CBD_MP4_(D)E₁₀ conjugate on Swiss webster fracture-bearing mice (n=5) after 3 weeks. Work to fracture represents the total amount of energy absorbed by the healed femur before it refractured in a postmortem 4 point bend analysis. Work to fracture is a measure of how strong the bone is at the site of fracture repair 1×, 10×, and 100× are respectively 1 nmol, 10 nmol, and 100 nmol of the conjugate delivered daily by subcutaneous injection. The CBD_MP4_(D)E₁₀ conjugate improves bone strength at the fracture calluses three weeks post fracture. 

1-19. (canceled)
 20. A compound having a structure of: X-Y-Z wherein: X is an extracellular matrix component, a fragment of an extracellular matrix component, or an agent that activates an extracellular matrix component; Y is absent or a linker; and Z is a bone-targeting molecule; or a pharmaceutically acceptable salt thereof.
 21. The compound of claim 20, wherein Z comprises a polypeptide.
 22. The compound of claim 20, wherein Z comprises not less than 4 and not more than 40 amino acid residues.
 23. The compound of claim 22, wherein at least one amino acid is aspartic acid or glutamic acid.
 24. The compound of claim 20, wherein Z comprises not less than 6 and not more than 20 D-glutamic acid residues.
 25. The compound of claim 24, wherein Z is 10 D-glutamic acid residues.
 26. The compound of claim 20, wherein Z comprises not less than 6 and not more than 20 D-aspartic acid residues.
 27. The compound of claim 26, wherein Z is 10 D-aspartic acid residues.
 28. The compound of claim 20, wherein Y is a releasable linker or a non-releasable linker.
 29. The compound of claim 28, wherein the releasable linker comprises at least one releasable linker group, each releasable linker group being independently selected from the group consisting of a disulfide (S-S), an ester, and a protease-specific amide bond.
 30. The compound of claim 28, wherein the non-releasable linker comprises at least one non-releasable linker group, each non-releasable linker group being independently selected from the group consisting of a carbon-carbon bond and an amide.
 31. The compound of claim 28, wherein Y comprises one or more ethylene glycol units.
 32. The compound of claim 31, wherein Y comprises 2-8 oxyethylene units.
 33. The compound of claim 20, wherein the extracellular matrix component is selected from the group consisting of a laminin, a fibronectin, and an osteopontin fragment.
 34. The compound of claim 33, wherein the laminin is selected from the group consisting of a laminin fragment (IKVAV) and Ln2-P3.
 35. The compound of claim 33, wherein the fibronectin is selected from the group consisting of PHSRN and ITGA.
 36. The compound of claim 33, wherein the osteopontin fragment is selected from the group consisting of a collagen binding motif, a osteopontin derived peptide, and a collagen binding domain.
 37. The compound of claim 20, wherein the agent that activates the extracellular matrix component is an integrin ligand.
 38. The compound of claim 37, wherein the integrin ligand is selected from the group consisting of ITGaS cys, ITGA stb-KD, ITGA stb-KE, ITGA stb-DAPE, and ITGA stb-DAPD.
 39. The compound of claim 20, wherein the extracellular matrix component is selected from the group consisting of chemotatic collagen (CTC), P15, and DGEA. 